Gen 1 2007 MPS clutch master cylinder problem!

I have a built motor with single mass flywheel and Southbend Stage 3 clutch. I've been trying to solve the issue since the build of clutch occasionally sticking or releasing slowly, so installed braided hose, but it appears the master cylinder is just not strong enough for the spring loading in the S3 clutch. When the clutch pedal is pressed in, (we think!) fluid leaks behind the diaphragm or piston and jams the clutch down or makes a slow release as the fluid works its way back to the drive side. I have a new "crossover" master cylinder installed now and that is failing just like the OEM part.
The big boys must have had the same issue! What's the solution?
TIA!

Sorry if this is a blunt but it sounds like your new "crossover" master cylinder is shagged and in need of a parts warranty claim. I'd get an independent eye to go over the assemblies - someone who is familiar with the vehicles, and presuming the new master cylinder is faulty, replace it.